I'm making a website for someone and need to know how to go about transferring the domain name. The site is currently hosted by the web design company, but when I checked WHOIS, the registrant is someone else. The name servers belong to the web design company. Who do I need to request the transfer from? Is it the registrar or the registrant? And what information do I need to give them?
You need to request registrant as he owns the domain. You need to give your account details of registrar like name.com, godaddy. Then he'll transfer to that account.
Your client needs to give you the username and password for the domain's control panel. Does the email address In the WHOIS belong to your client? If so, then your client can just do a 'forgot password' to retrieve the info. If not then he has to contact the host to get the WHOIS info changed to his name. The host will not give you, a third party, access to the domain. You can change the nameservers after your client gives you access to the domain's control panel.
You need to determine where the domain was registered at, and obtain the authorisation code / EPP code in order to transfer that domain to another registrar if you want to do that. Make sure the domain is unlocked in order for the transfer to succeed.